1. Field of the Invention
The present invention relates to a polarized electromagnetic relay.
2. Description of the Related Art
An electromagnetic relay including at least one pair of normally open contacts and at least one pair of normally closed contacts, in which the pair of normally open contacts and the pair of normally closed contacts perform an opening or closing operation in a manner mechanically interlocked with each other in accordance with the movement of an armature, and the individual pair of contacts are arranged insulated from one another, has been known. This type of electromagnetic relay can be used as, e.g., a relay with forcibly guided contacts (also referred to as a safety relay) in which, the failure of any normally open contact to open (e.g., due to welding) has the effect that none of the normally closed contacts close even when the relay is not energized. A circuit incorporating such a safety relay can detect the welding of the pair of normally open contacts and can maintain a power shutoff condition.
An electromagnetic relay having a forcibly guided contact configuration is described in, e.g., Japanese Unexamined Patent Publication (Kokai) No. 6-176676 (JP6-176676A). The electromagnetic relay described in JP6-176676A includes an actuating member operating against the biasing force of a return spring in accordance with the swinging motion of an armature moving like a hinge, and is constructed so that a pair of normally open contacts and a pair of normally closed contacts perform an opening or closing operation in a manner mechanically interlocked with each other in accordance with the movement of the actuating member and the pair of normally open contacts and the pair of normally closed contacts can never be simultaneously in closed position. The actuating member moves in a direction perpendicular to the center axis of a coil of an electromagnet used to operate the armature. The electromagnet is placed so that the center axis of the coil is oriented perpendicularly to the bottom face of the relay.
On the other hand, in a polarized electromagnetic relay including the combination of an electromagnet and a permanent magnet, it is known to provide a low-profile configuration in which the electromagnet is placed so that the center axis of a coil is oriented in parallel to the bottom face of the relay, and in which an armature with the permanent magnet attached thereto is reciprocated in a direction parallel to the center axis of the coil (refer to, e.g., Japanese Unexamined Patent Publication (Kokai) No. 2008-210776 (JP2008-210776A)). The polarized electromagnetic relay described in JP2008-210776A has a so-called transfer-type contact configuration, comprising a single movable contact spring member that supports a movable make (or normally open) contact and a movable break (or normally closed) contact in a back-to-back configuration, a first fixed contact terminal member that supports a fixed make (or normally open) contact capable of contacting and separating from the movable make contact, and a second fixed contact terminal member that supports a fixed break (or normally closed) contact capable of contacting and separating from the movable break contact.